A theoretical study of the Curtius rearrangement. The electronic structures and interconversions of the CHNO species

1977 ◽  
Vol 55 (9) ◽  
pp. 1498-1510 ◽  
Author(s):  
Arvi Rauk ◽  
Paul F. Alewood
Keyword(s):  
Electronic Structures ◽  
Theoretical Study ◽  
Electronic States ◽  
Decomposition Products ◽  
Curtius Rearrangement ◽  
Nitrile Oxides ◽  
Photochemical Decomposition ◽  
Degenerate States ◽  
Scf Calculations ◽  
Lcao Mo

The thermal and photochemical decomposition of formyl azide in the Curtius rearrangement has been studied by means of RHF–LCAO–MO–SCF calculations augmented by CI. The lower electronic states of carbonyl azides, carbonyl nitrenes, isocyanates, cyanates, oxazirenes, nitrile oxides (fulminates), and isofulminates are discussed on the basis of the results for formyl azide and the corresponding isomers of formula CHNO. The discovery of two nearly degenerate states of A′′ symmetry for formyl azide which may channel decomposition products directly to both isocyanates and carbonyl nitrenes explains some puzzling features of the photolytic Curtius rearrangement. The interconvertibility of the CHNO isomers (and the RCNO isomers) is discussed in terms of the energetics and intended correlations of the accessible electronic states of these species.

A comparative theoretical study of the electronic structure of some nickel(II) azides, thiocyanates, and isothiocyanates

1998 ◽  
Vol 76 (7) ◽  
pp. 1006-1014 ◽  
Author(s):  
R H Abu-Eittah ◽  
M El-Esawy ◽  
N Ghoneim ◽  
A T Aly
Keyword(s):  
Electronic Structure ◽  
Electronic Structures ◽  
Theoretical Study ◽  
Molecular Orbitals ◽  
Basis Sets ◽  
Theoretical Treatment ◽  
Double Zeta ◽  
Experimental Values ◽  
Scf Calculations ◽  
Split Valence

The electronic structure, conformation, and molecular orbitals of some nickel(II) azides, thiocyanates, and isothiocyanates have been studied. Three different basis sets: split valence (SV), split valence with six d-Gaussians (SV6D), and double zeta (DZ) sets, were used to find the best ground state for nickel. It has been found that the combination, DZ-3F, gives results closest to the experimental values. The electronic structures of the nickel azides studied were completely different from those of the nickel thiocyanates. On the other hand, the electronic structures of the nickel thiocyanates studied were highly comparable to those of the corresponding nickel isothiocyanates. Molecular orbitals were computed for the complexes studied and the types of electronic transitions expected were identified and discussed.Key words: Ni(II) azides, thiocyanates, and isothiocyanates: ab initio SCF calculations; MO calculations on some Ni(II) complexes; theoretical treatment of some Ni(II) ions and salts; geometry and energetics of some nickel(II) azides, thiocyanates, and isothiocyanates.

A Theoretical Study of the Site of Protonation of Formamide Using Non-empirical LCAO-MO-SCF Calculations

1973 ◽  
Vol 51 (9) ◽  
pp. 1432-1434 ◽  
Author(s):  
Alan C. Hopkinson ◽  
Imre G. Csizmadia
Keyword(s):  
Proton Affinity ◽  
Molecular Orbital ◽  
Theoretical Study ◽  
Molecular Orbital Calculations ◽  
Scf Calculations ◽  
Lcao Mo

Molecular orbital calculations are used to show that O-protonated formamide is more stable than its N-protonated tautomer by 6.2 kcal/mol. The computed proton affinity of formamide (assuming O-protonation) is computed to be 254.8 kcal/mol.

THE LOWER EXCITED STATES OF SOME SIMPLE MOLECULES

1958 ◽  
Vol 36 (1) ◽  
pp. 10-23 ◽  
Author(s):  
R. S. Mulliken
Keyword(s):  
Absorption Spectra ◽  
Excited States ◽  
Strong Evidence ◽  
Electronic States ◽  
Ultraviolet Absorption ◽  
Mo Calculations ◽  
New Interpretation ◽  
Simple Molecules ◽  
Scf Calculations ◽  
Lcao Mo

The present and prospective rapidly increasing usefulness of good LCAO-MO calculations on the electronic states of simple molecules in the interpretation of observed excited states is pointed out. As examples, the observed and predicted states of, in particular, the π3π configurations of N2 and CO are compared with those of C2H2 and HCN and with those of CO2 and CS2. Further, the results of LCAO-SCF calculations on CO2 and on O3 are surveyed, and it is shown how these can be helpful in interpreting and understanding the ground and excited states of AB2 (expecially AO2) molecules in general. A new interpretation of the so-called d3П state of CO as a case b πu3πg, 3Δu state is proposed. Tentative interpretations of some of the ultraviolet absorption spectra of C2H2, HCN, and of a number of AB2 molecules are reviewed or suggested, including some discussion of the shapes of excited states. The AB2 discussion is a revision of one given earlier. Finally, following up a suggestion of Coon, it is pointed out that there exists strong evidence for slightly unequal A—O distances in certain excited states of C1O2 and SO2.

scholarly journals An MO-Theoretical Study of the Electronic Structures of Formyloxyl and Acetoxyl Radicals

1977 ◽  
Vol 50 (5) ◽  
pp. 1339-1340 ◽  
Author(s):  
Osamu Kikuchi ◽  
Kayoko Utsumi ◽  
Keizo Suzuki
Keyword(s):  
Electronic Structures ◽  
Theoretical Study

Theoretical study on the spectroscopic properties of the low-lying electronic states and the laser cooling feasibility of the CaI molecule

2021 ◽  
pp. 107709
Author(s):  
Dong-Ying Li ◽  
Chuan-Lu Yang ◽  
Zhao-Peng Sun ◽  
Mei-Shan Wang ◽  
Xiao-Guang Ma
Keyword(s):  
Laser Cooling ◽  
Theoretical Study ◽  
Electronic States ◽  
Spectroscopic Properties

Theoretical study on dinitrogen complexes. Relation between facility of protonation and difference of electronic structures of d6 and d8 complexes

1984 ◽  
Vol 62 (7) ◽  
pp. 1329-1332 ◽  
Author(s):  
Kenzi Hori ◽  
Tokio Yamabe
Keyword(s):  
Electronic Structures ◽  
Theoretical Study ◽  
Nitrogen Molecule ◽  
Dinitrogen Complexes

Electronic structures of different d configurations have been studied in relation to the facility of protonation to dinitrogen ligand in Cr(0) and Co(I) complexes. The d6 Cr complex has much better MO's for protonation than the d8 Co complex. This difference largely affects the protonation energies and the reduction of nitrogen molecule in these complexes.

History and Cross-Disciplinary Perspective of Compositional Imaging and Mapping With Nexafs Microscopy

1998 ◽  
Vol 4 (S2) ◽  
pp. 154-155
Author(s):  
H. Ade
Keyword(s):  
Electronic Structures ◽  
Chemical Shifts ◽  
Electronic States ◽  
Inorganic Materials ◽  
Chemical Bonds ◽  
Fundamental Physics ◽  
X Ray ◽  
Disciplinary Perspective ◽  
Core Electrons ◽  
X Ray Absorption

In Near Edge X-ray Absorption Fine Structure (NEXAFS) microscopy, excitations of core electrons into unoccupied molecular orbitals or electronic states provide sensitivity to a wide variety of chemical functionalities in molecules and solids. This sensitivity complements infrared (IR) spectroscopy, although the NEXAFS spectra are not quite as specific and “rich” as IR spectra. The sensitivity of NEXAFS to distinguish chemical bonds and electronic structures covers a wide variety of samples: from metals to inorganics and organics. (There is a tendency in the community to use the term NEXAFS for soft x-ray spectroscopy of organic materials, while for inorganic materials or at higher energies X-ray Absorption Near Edge Spectroscopy (XANES) is utilized, even though the fundamental physics is the same.) The sensitivity of NEXAFS is particularly high to distinguish saturated from unsaturated bonds. NEXAFS can also detect conjugation in a molecule, as well as chemical shifts due to heteroatoms.

Theoretical study of the transition probabilities among the three lowest electronic states of the SeS molecule

1988 ◽  
Vol 64 (4) ◽  
pp. 725-738 ◽  
Author(s):  
J.R. Alvarez-Collado ◽  
R.J. Buenker
Keyword(s):  
Theoretical Study ◽  
Transition Probabilities ◽  
Electronic States

SEMIEMPIRICAL SCF–LCAO–MO TREATMENT OF THIOPHENE, FURAN, AND PYRROLE

1965 ◽  
Vol 43 (5) ◽  
pp. 1569-1576 ◽  
Author(s):  
N. Solony ◽  
F. W. Birss ◽  
John B. Greenshields
Keyword(s):  
Experimental Data ◽  
Satisfactory Agreement ◽  
Electronic Structures ◽  
Spectroscopic Data ◽  
Variable Parameter ◽  
Coulomb Repulsion ◽  
Resonance Integral ◽  
Electronic Transitions ◽  
The Core ◽  
Lcao Mo

The semiempirical SCF–LCAO–MO method of Pariser–Parr–Pople is utilized in the study of the π-electronic structures of thiophene, furan, and pyrrole. The core Hamiltonian expansion contains a Uz++ term, the potential due to the ionized hetero-atom contributing two electrons to the π-system. The γzz, one-center coulomb repulsion integral for the hetero-atom is evaluated from the experimental spectroscopic data only. With the resonance integral βczc as the only variable parameter, the calculated π*–π electronic transitions are in a satisfactory agreement with the experimental data.

Theoretical Study of Electronic Structures of [Peroxoporphinato]manganate [Mn(P)(O2)]−Anion

2006 ◽  
Vol 79 (8) ◽  
pp. 1201-1210 ◽  
Author(s):  
Yasunori Yoshioka ◽  
Hideaki Sano ◽  
Masaki Mitani
Keyword(s):  
Electronic Structures ◽  
Theoretical Study
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